const {series, parallel} = require('gulp') 


const task1 = done => {
    setTimeout(() => {
        console.log('task1 working~')
        done()
    }, 1000);
}
const task3 = done => {
    setTimeout(() => {
        console.log('task3 working~')
        done()
    }, 1000);
}
const task2 = done => {
    setTimeout(() => {
        console.log('task2 working~')
        done()
    }, 1000);
}
//series 按照顺序 依次串行执行任务
exports.foo = series(task1, task2, task3)
//parallel 并行执行任务
exports.bar = parallel(task1, task2, task3)